Furnace blow pipes



May 17, 1960 F. J. BORON FURNACE BLOW PIPES Filed Aug. 18, 1958INVENTOR. FRANK J. BoRoN BY WM H t-P 5 a balance.

2,937,018 FURNACE BLOW mrns Frank I. Boron, Elyria, Ohio, assign'or toAmerican Brake Shoe Company, Wilmington, Del., a corporation of DelawareApplication August 18, 1958, Serial No. 755,732 2 Claims. Cl. 266-30)This invention relates to the construction of blow pipes of the kindassociated with tuyeres in a blast furnace.

Air for sustaining combustion ,in a blast furnace is introduced into thesmelting areathrough a tuyere. This air is furnished under pressure by apipe in the form of a so-called tuyere stock, and the blow pipe isinter- 2,937,018 Patented May 17, 1960 ICC ject to rather severe thermalgradients between the tuyere posed between the tuyere and thetuyerestock. Historically, tuyere blow pipes are made of'cast iron, andthis is especiallyso in view of the peculiar end constructions at thetwo ends of the blow pipe respectively affording the stock joint and thetuyere joint. While acast iron blow pipe represents a relatively heavy,ruggedvand easily cast part, cast iron is not ordinarily considered athermally resistant material, and I have discovered in accordance withthe present invention that a sound, high quality blow pipe can be castfrom an expensive heatresistant alloy flowing at high temperatures, inspite of its peculiar shape which would ordinarily discourage use ofsuch alloys, and I accomplish this by in effect dividing the blow pipeinto three sections such that an intermediate section of uniformdiameter is centrifugally cast and the two end sections are cast inconventional sand molds. By so casting and constructing a blow pipe, Iam able to afford a blow pipe of lighter metal sections in contrast tocast iron blow pipes, and I am able to afford a blow pipe representingan exceptionally sound casting for a part-of this kind warranting use ofexpensive heatresistant alloys assuring prolonged thermal life of theblow pipe. These achievements represent the primary objects of thepresent invention.

Other and further objects of the present invention will be apparent fromthe following description and claims and are illustrated in theaccompanying drawings which, by way of illustration, show a preferredembodiment of the present invention and the principle thereof and Whatis now considered to be the best mode contemplated for applying thatprinciple. Other embodiments of the invention embodying the same orequivalent principles may be used and structural changes may be made asdesired by those skilled in the art without departing from the presentinvention and the purview of the appended claims.

In the drawings:

Figs. 1 and 2 are respectively perspective views in opposed attitudes ofa blow pipe constructed in accordance with the present invention; and

Fig. 3 is a somewhat schematic sectional view showing the blow pipe ofthe present invention in its installed state.

In contrast to the standard one-piece cast iron blow pipe in the priorart, a blow pipe in accordance with the present invention is fabricatedfrom three separately cast parts, each of which is preferably cast froma heat-resistant alloy analyzing approximately as follows: chromium, 10to 30 percent; nickel, 5 to 60 percent; carbon, 0.1 to 0.8 percent;nitrogen, 0.05 to 0.3 percent; iron, The foregoing analysis is, asmentioned, used for all three parts of the present pipe to be describedhereinafter, but where a particular installation is subandstock end ofthe blow pipe then it is possible that heat-resistant alloys ofdifferent analyses will be used for the several sections of the blowpipe in accordance with the type of thermal stressing expected to beencountered.

-In Figs. 1 and 2 of the drawings, there is shown in perspective two endviews of a blow pipe constructed in accordance with the presentinvention, but so far as shape and configuration are concernedit will beappreciated that this blow pipe 10 is for the most part identical'to astandard blow pipe of cast iron-construction.

Considering the variant-section thickness and configurations embodiedinthe blow pipe 10, it will be realized that these represent parts whereinit is extremely difficult to achieve a sound, acceptable casting fromexpensive heat-resistant alloys which must be cast at relatively hightemperatures in contrast to cast iron which flows at lower temperatures,and this is especially so in view of the fact that the blow pipeillustrated in Figs. 1 and 2 is approximately four feet in over-alllength. In fact, these considerations would ordinarily preclude any ideathat such a blow pipe could be cast from alloys which flow only at hightemperatures, since some porosity, wall thickness fluctuations anddiameter fluctuations of an unacceptable degree would be expected. Inthis connection,

: it should be pointed out that the tuyere end 14 of the blow pipe 10has an outside diameter of approximately ten inches and the outsidediameter of the tuyere stock end 15 has an outside diameter ofapproximately thirteen and one-half inches.

In accordance with the present invention, I have discovered that it isin fact possible to construct a blow pipe for blast furnaceinstallations from an expensive heatresistant alloy which must be castat relatively high temperatures by casting the intermediate section 16of the blow pipe (which is of uniform diameter throughout)centrifugally, and casting the two end parts 14 and 15 separately inconventional stationary sand molds. Thus, as shown in Fig. 3, it willbenoted that the intermediate section 16 is of uniform inside and outsidediameter and has ends 17 and 18 defined by annular faces.

The tuyere end or joint 14 is cast in a sand mold to include arelatively short stub sleeve or collar 20 having an end 21 which is ofthe same inside and outside diameter as the corsresponding end 18 of theintermediate tube section 16. The tuyere end or joint 14 forward of thestub portion 20 is cast on the outside with an enlarged annular flange22, and as shown particularly in Figs. 2 and '3 the outer surface ofthis flange is tapered at 2'2T inwardly proceeding in a forwarddirection so as to complementally engage the inside of the furnacetuyere T which is mounted in the side wall SW of the blast furnace. Thetuyere of course includes an opening TO which is coaxial with the insidechamber in the blow pipe 10 through which air or other oxygen-containingcombustion supporting medium is directed to emit from the tuyere T.

The opposite end of the blow pipe 10 is to be joined to the stock pipeSP which is located externally of the blast furnace and which conductsthe gaseous medium from the so-called bustle pipe BP. Thus, the stockend or joint 15 of the blow pipe 10 includes an annular stub sleeve 25which has an end 26, Fig. 1, having the same 3 16 are chamfered at CH,Fig. 3, and the corresponding ends 21 and 26 of the end sections 14 and15 are correspondingly chamfered so that when the three sections arejoined in the desired end-toend relationship there results an annularrecess of V-section enabling weldments W1 and W2 to be laid thereinthereby rigidly joining the three sections of the blow pipe.

- Reference has been made above to dimensions in this instance in orderthat an appreciation can be had of the relatively large sized parts thatare cast under the present invention. In this connection, it should bementioned that it has been found that intermediate section as 16 of sixand eight foot lengths can be cast centrifugally from the abovespecified alloy with a very high degree of soundness, since it is notnecessary to resort to gates and risers. Moreover, the presentconstruction enables section thicknesses and diameters to be controlledWithin & of an inch, and of course all of this is made possible in thepresent instance by the realization that the two end pieces 14 and 15should be separately cast in conventional stationary molds. Accordingly,it is possible to obtain a high degree of soundness in each of the threemembers of the three-piece blow pipe in the present instance, andaccordingly resort to a heat-resistant alloy is warranted and madepossible.

Hence, while I have illustrated and described a preferred embodiment ofmy invention, it is to be understood that this is capable of variationand modification, and I therefore do not wish to be limited to theprecise details set forth, but desire to avail myself of such changesand alterations as fall within the purview of the following claims.

I claim:

1. A blast furnace or like blow pipe to be located between a tuyereand atuyere stock pipe and comprising, a center part consisting of acentrifugally cast elongated central tube section of a heat-resistantalloy and having substantially uniform inside and outside diametersthroughout, said tube section having an inner end to be disposed towardthe tuyere and an outer end to be disposed toward the tuyere stock pipe,a separate sand-cast tuyere joint head of a heat-resistant alloy joinedto the 4 inner end of said tube section, and a separate sand-cast stockpipe joint head of a heat-resistant alloy joined tothe outer end of saidtube section, said alloy consisting essentially of and analyzingapproximately as follows: chromium, 10 to 30 percent; nickel 5 to 60percent; carbon, 0.1 to 0.8 percent; nitrogen, 0.05 to 0.3 percent;iron,

balance.

2. A blast furnace or like blow pipe to be located between a tuyere anda tuyere stock pipe and consisting essentially of but three main parts,namely, a centrifugally cast elongated central tube section partconsisting of a centrifugally cast tube of a heat-resistant alloy havingsubstantially uniform inside and outside diameters throughout, saidcentrifugally cast tube section having an inner end to be disposedtoward the tuyere and an outer end to be disposed toward the tuyerestock pipe, a separate sand-cast tuyere joint head part of aheat-resistant alloy welded to the inner end of said centrifugally casttubesection, said tuyere joint head part having an end surfaceconfigured complemental to the surface of the tuyere'with which it is tobe associated, and another separate sand-cast stock pipe joint head partof a heatresistant alloy welded to the outer end of said tube section,said other head part having an end surface configured complemental tothe surface of the end of the tuyere stock pipe with which it is to beassociated, said alloy consisting essentially of and analyzingapproximately as follows chromium, '10 to 30 percenttnickel 5 to 60percent; carbon, 0.1 to 0.8 percent; nitrogen, 0.05 to 0.3 percent;iron, balance.

References Cited in the file of this patent UNITED STATES PATENTS1,844,194 Maltitz Feb. 9, 1932 2,023,025 McKee Dec. 3, 1935- FOREIGNPATENTS 736,098 Great Britain Aug. 31, 1955 OTHER REFERENCES E. W. Doe:Foundry Work, John Wiley.& Sons, pages -48,1951.

